Two studies concerning low molecular weight organic acids in soils
were conducted. In the first study, anion exclusion chromatography was
used to separate and identify 12 common organic acids, and the accuracy,
precision and detection limits of the method were determined. The method
was found to be sensitive and accurate to between 1.5 and 9 ��M,
depending on the acid in question. The stability of the selected acids was
examined, and the large concentration changes observed underscore the
importance of timely analysis of soil solutions. No significant interferences
were encountered in the analysis of two soil solutions. In the second
study, the reaction of a forest soil with oxalic acid at four concentrations
was monitored for a period of 96 hours. A large release of aluminum,
sulfate, and phosphate was observed, with the greatest release occurring
with the highest concentration of added oxalate. Solution aluminum
increased by up to a factor of twenty, and though [Al�����] values were
consistent with control by thermodynamic equilibrium with an amorphous
aluminum oxide phase, exchangeable Al appeared to be the source of the
increase. Sulfate increased abruptly at the start of the reaction and
continued to rise, though more slowly, throughout the study. Solution
phosphate was increased by up to four times and was maintained at the
elevated level throughout the study. Changes in both sulfate and
phosphate concentrations were attributed directly to exchange with oxalate.
The persistence of elevated phosphate concentrations after 96 hours
indicates that the effects of oxalate production by mycorrhizae could have
lasting effects on the nutrient status of a soil. / Graduation date: 2000
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33172 |
| Date | 12 November 1999 |
| Creators | Hayden, John |
| Contributors | Baham, John E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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